Mortality in Myasthenia Gravis in Denmark From 1985 to 2020: A Population-Based Cohort Study.

Abstract

Myasthenia gravis (MG) is a life-threatening disease associated with elevated mortality, primarily in the first years after diagnosis. We determined short-term (<1 year) and long-term (1-5 years) mortality for patients with MG compared with the general population. Using nationwide health registers, we identified patients with MG and matched 1:10 with the general population by age, sex, and diagnostic index date from 1985 to 2020. We calculated matched hazard ratios (HRs) using Cox regression analysis, stratified by sex, age, period, and baseline comorbidities, and performed comorbidity-adjusted analyses. Our cohort encompassed 2,110 patients (50.2% female) and 21,100 from the general population, with 77.3% aged younger than 75 years. Short-term cumulative mortality was 4.8% in patients with MG and 2.6% in the general population, yielding a HR of 1.8 (95% CI 1.5-2.3). Long-term mortality was 1.3 (95% CI 1.1-1.5). Short-term mortality rose from 2015 to 2020, especially in patients aged 75 years or older (HR 2.8, 95% CI 1.8-3.6). Comorbidity-adjusted analyses decreased short-term mortality (HR 1.6, 95% CI 1.3-2.0), and long-term mortality aligned with the general population. MG mortality remains elevated, especially in the first year after diagnosis in older patients, underlining the importance of early intervention and close monitoring.